Internal Angle Research Articles

ACES: Optimized Alchemically Enhanced Sampling.

We present an alchemical enhanced sampling (ACES) method implemented in the GPU-accelerated AMBER free energy MD engine. The methods hinges on the creation of an "enhanced sampling state" by reducing or eliminating selected potential energy terms and interactions that lead to kinetic traps and conformational barriers while maintaining those terms that curtail the need to otherwise sample large volumes of phase space. For example, the enhanced sampling state might involve transforming regions of a ligand and/or protein side chain into a noninteracting "dummy state" with internal electrostatics and torsion angle terms turned off. The enhanced sampling state is connected to a real-state end point through a Hamiltonian replica exchange (HREMD) framework that is facilitated by newly developed alchemical transformation pathways and smoothstep softcore potentials. This creates a counterdiffusion of real and enhanced-sampling states along the HREMD network. The effect of a differential response of the environment to the real and enhanced-sampling states is minimized by leveraging the dual topology framework in AMBER to construct a counterbalancing HREMD network in the opposite alchemical direction with the same (or similar) real and enhanced sampling states at inverted end points. The method has been demonstrated in a series of test cases of increasing complexity where traditional MD, and in several cases alternative REST2-like enhanced sampling methods, are shown to fail. The hydration free energy for acetic acid was shown to be independent of the starting conformation, and the values for four additional edge case molecules from the FreeSolv database were shown to have a significantly closer agreement with experiment using ACES. The method was further able to handle different rotamer states in a Cdk2 ligand identified as fractionally occupied in crystal structures. Finally, ACES was applied to T4-lysozyme and demonstrated that the side chain distribution of V111χ1 could be reliably reproduced for the apo state, bound to p-xylene, and in p-xylene→ benzene transformations. In these cases, the ACES method is shown to be highly robust and superior to a REST2-like enhanced sampling implementation alone.

Analysis of Internal Nasal Valves Shapes and Angle due to Nasal Obstruction in Asian Nose

BACKGROUND
 Internal nasal valve (INV) is widely discussed because it is believed to have a role in structural nasal obstruction. Caucasian has a rather acute angle of INV due to the known geometric of their nose. Whilst Asian generally has broader, thicker, and bigger anthropometric proportion of nose than Caucasian. Asia is vastly diverse in ethnicity, one can only assume that Asian INV may be differ in shape and larger in angles compare to Caucasian, due to the minimum publication addressing this issue.
 AIM
 To report the anatomy of INV and its angle in obstructed Asian noses.
 METHOD
 A case control study was conducted. Forty cases of nasal obstruction and 80 controls without nasal obstruction. Both groups were evaluated using Nasal Obstruction Symptom Evaluation (NOSE) questionnaire, rigid nasal endoscopy and active anterior rhinomanometry (AAR). Anatomy and angle of INV was later measured using digital image analysis.
 RESULT
 Six basic INV shapes were seen throughout both groups, many has different shape combinations. Most commonly (more than 60%) observed shape in both groups were the occupied by nasal septal body (NSB). The right INV angle in case group was 15,5º ± 10,1º (p = 0,123) and left INV angle was 17,2º ± 9,0º (p = 0,022). In control group, the right INV angle was 19,6º ± 11,8º (p = 0,123) and left INV angle was 23,2º ± 12,5º (p = 0,022).
 CONCLUSION
 It is shown that most common shape of Asian INV in both groups, is the occupancy by NSB. Internal nasal valve angle in obstructed nose is narrower in comparison to those without nasal obstruction. This study also demonstrates Asian, particularly Indonesian, has a wider angle than Caucasian.

Separation of Diclofenac Sodium Using Polysulfone Membranes Incorporated with Manganese Nanoparticles

AbstractMembranes are employed in various applications, including pharmaceutical waste separation, owing to their operability, high removal capacity, and cost‐effectiveness. However, membrane fouling is an influential factor that reduces their efficiency. Since the addition of hydrophilic inorganic components has been shown to reduce membrane fouling, the present work focuses on manganese (MnO2, Mn2O3) nanoparticles (NP) in polysulfone (PSF) casting solutions to prepare mixed‐matrix membranes for separating diclofenac (DCF) sodium from an aqueous solution. The membranes were characterized using microscopic and spectroscopic techniques, thermogravimetric analysis, and by elucidating the internal membrane specific area, contact angle, and mechanical properties. The synthesized NP were characterized by X‐ray diffraction and transmission electron microscopy analysis. The concentrations of DCF sodium measured in the feed and filtrate solutions showed that the PSF/Mn2O3 membrane provided the highest permeate flux with good DCF removal of 98.4 %. Mechanical testing indicated that higher tensile strength was obtained when embedding MnO2 NP in the PSF membrane matrix. Contact angle measurements showed an improvement of the surface hydrophilicity when blending the PSF casting solution with MnO2 NP. The fouling test indicated that the PSF/Mn2O3 membrane provided the best antifouling properties. Thus, NP addition enhanced the porosity, antifouling characteristics, hydrophilicity, and water flux of the fabricated membranes.

The reliability of lower limb 3D gait analysis variables during a change of direction to 90- and 135-degree manoeuvres in recreational soccer players.

Several biomechanical outcomes are being used to monitor the risk of injuries; therefore, their reliability and measurement errors need to be known. To measure the reliability and measurement error in lower limb 3D gait analysis outcomes during a 90∘ and 135∘ change of direction (COD) manoeuvre. A test re-test reliability study for ten healthy recreational players was conducted at seven-day intervals. Kinematics (Hip flexion, adduction, internal rotation angles and knee flexion abduction angles) and kinetics (Knee abduction moment and vertical ground reaction force) data during cutting 90∘ and 135∘ were collected using 3D gait analysis and force platform. Five trials for each task and leg were collected. Standard error of measurement (SEM) and the intraclass correlation coefficient (ICC) were calculated from the randomised leg. The ICC values of the kinematics, kinetics, and vertical ground reaction force (VGRF) outcomes (90∘ and 135∘) ranged from 0.85 to 0.95, showing good to excellent reliability. The SEM for joint angles was less than 1.69∘. The VGRV showed a higher ICC value than the other outcomes. The current study results support the use of kinematics, kinetics, and VGRF outcomes for the assessment of knee ACL risk in clinic or research. However, the hip internal rotation angle should be treated with caution since the standard measurement error exceeded 10% compared to the mean value. The measurement errors provided in the current study are valuable for future studies.

Contribution of higher-order structure to perception of mirror symmetry: Role of shapes and corners.

Visual mirror symmetry is a global feature that is dependent on specific low-level relationships between component elements. Initially conceptualized as virtual lines between paired elements, it has been suggested that higher-order structure between pairs of symmetric elements forming virtual four cornered shapes may also be important for strengthening the percept of mirror symmetry. We utilize corner elements, formed by joining two Gabor elements along a central midline creating vertices with variable internal angles, in a temporal integration paradigm. This allows us to specifically manipulate the presence and type of higher-order versus lower-order structure in patterns with symmetrically placed elements. We show a significant contribution of higher-order structure to the salience of visual symmetries compared with patterns with only lower-order structures. We also find that although we are more sensitive to patterns with higher-order structure, there is no difference in the temporal processing of higher-order versus lower-order patterns. These findings have important implications for existing spatial filter models of symmetry perception that rely on lower-order structures alone and reinforces the need for elaborated models that can more readily capture the complexities of real-world symmetries.

The influence of molecular shape on glass-forming behavior in a minimalist trimer model.

In this study, we employed molecular dynamics simulations to probe the influence of molecular morphological changes on the dynamic behavior of a model consisting of trimer molecules. This model, comprising a chain of three particles, facilitates the exploration of variations in the internal angle between these particles. Our findings highlight the significant impact of molecular conformation: systems with more linear conformations, characterized by larger internal angles, exhibit relaxation times several orders of magnitude greater than their counterparts with smaller internal angles. Furthermore, we delve into the role of angular interaction rigidity, uncovering a pronounced deceleration in dynamics and an increase in dynamic heterogeneity as rigidity escalates. This model not only provides insights into azobenzene-type systems but also sets the stage for subsequent research into the microscopic nuances of related systems, with potential extensions to composite systems.

Radiation-Associated Cardiotoxicity during Breast Cancer Treatment with Ionizing Radiation

Introduction: Breast cancer is the most common cancer in women. The treatment of breast carcinoma has advanced in the last decade and nowadays there are treatment protocols for all stages of the disease. Depending on the histopathology and stage breast cancer is treated with surgery, chemotherapy and radiotherapy. Regarding radiation, the field of irradiation includes the chest wall in patients with mastectomy, or the breast glandular tissue in patients with conserving surgical approaches. It is often treated with radiation therapy with two opposing tangential fields, and when indicated supraclavicular lymph nodes have to be irradiated. In this case an additional anterior field is applied. The tangential as well as the other radiation beams have a potential damaging effect on the healthy surrounding tissues, particularly over the heart in the left breast irradiation and in the lungs as well. Material and Methods: The study included 25 patients with left breast carcinoma, all post surgery, treated with radiation therapy, with the Elekta accelerator at our department. For academic purpose the treatment plans were generated following two methods. The first one with two tangential opposite beams plus a supraclavicular beam. In this method the angles of the tangential internal and external create an angle that is equal to 180&#730 {310&#730& 130&#730}; no further changes were made to the beam geometry. Even though this is not the best option from the dose distribution point of view, it is still the most applied method, probably because of the semplicity of it. For each patient, a second plan was generated using two opposite tangential beams plus the supraclavicular beam. The angles of the internal and external beam were changed from 1&#730to 3&#730, depending on the surface of the body, so that the resulting angle was 180&#730± 3&#730 {310&#730± 3&#730& 130&#730± 3&#730} with the aim to adapt the beam geometry as much as possible to the shape of the thoracic wall and to spare the OAR-s. Results and Discussion: The data show that the dose in the organs at risk, in terms of dose percentage, is lower when the angles of the beams are changed with 1&#730-3&#730, compared to the classic method where the internal and external angles equal 180&#730. This dose is not only non-negligible but significant; for every angle change from 1&#730to 3&#730, there is a significant reduction in the integral dose in the radiated volume, expressed in percentage, up to 5%. Conclusion: In most centers, the radiation treatment of breast is realized with two tangential opposite beams, which usually are mirror beams, or in other words, the internal and external beam angles create an angle of 180&#730 {α + β = 180&#730}. This is a simple method, which provides a good dose distribution, but leaves a relatively high dose in the organs at risk. This study shows the difference in the dose percentage in the heart and lung when the beam angles are changed adapting to the anatomy of the patient. Reducing these doses allows for better overall treatment and less longtime toxicity, particularly for the heart tissues.

The CFD analysis of the effect of internal peak angle and mass-flow rates on the thermal performance of solar air heater with triangle cross-section

A new design of solar air heater with triangle cross-section is numerically studied. The thermal performance of solar air heater is studied at various mass-flow rates, inlet air temperatures, and solar irradiation intensities. The CFD model is developed using the software ANSYS FLUENT to study the fluid-flow and heat transfer in the solar air heater. The 3-D discretization is applied to study the thermal performance of solar collector with triangle cross-section. Mesh independence is performed in order to choose the adequate mesh. The discrete ordinate radiation model and the RNG k-? turbulence model are used to study the radiative heat transfer and the turbulent flow inside the solar air heater. Particularly, effects of different internal peak angles (145?,126?, 100?, 80?, and 67.5?) under different solar irradiation intensities (from 620-1081 W/m2) are studied to improve the thermal performance of the solar air heater. The results show a good agreement between the numerical model and the experimental data with an average error of 6%. The maximum outlet air temperature of the solar air heater reached 72 ?C for the geometries with 12 and 16 channels (internal peak angles of 80? and 67.5?, respectively) under mass-flow rate of 0.0264 kg/s. The thermal performances of the solar air heater with 16 and 12 channels are 24.2% higher than standard geometry, respectively for solar irradiation intensity of 1081 W/m2. The configuration with internal peak angle of 80? and 12 channels is selected as the optimal with a thermal efficiency of 79%, a low pressure drops compared to geometry with 16 channels and lower costs.

Calculating curvature through gradient descent and nonlinear regression: A novel mathematical approach to digital anatomical morphometry

BackgroundAngular projection measurements have long been an established approach in anatomical morphometry. However, many described projection angles are in reference to inherently curved structures, often oversimplifying their topologies. AimsThe objective of this study is to develop a quick, quantitative method for determining structural curvature from digital images. We aim to utilize readily-available software and statistical methods to extrapolate curvature from images and compare this new method to established angular measurements. MethodsProjection angulation and curvature was modeled on and assessed by the acromia of 50 dry scapulae. Digital images were taken at a known scale, perpendicular to the acromion, and then processed with ImageJ software. Angles were measured by the angle tool and for curvature, seven markers were placed along the external and internal margins of the acromion. Utilizing Excel's Solver function, the coordinate points were passed through a rotation matrix and optimized for second order regression. Solver was instructed to minimize the sum of squared estimated error between our measured and calculated coordinate values by manipulating the angle of point rotation and regression equation coefficients. ResultsSignificant differences were found between external, internal, and midline acromion measurements in both angles and curvatures. External angle = 80.8 (14.2)°; internal angle = 130.3 (13.6)°; midline angle = 105.6 (10.5)°; [reported as mean (SD)]. External curvature = 0.055 (0.015) mm−1; internal curvature = 0.035 (0.025) mm−1; midline curvature = 0.046 (0.017) mm−1; [reported as median (IQR)]. ConclusionsSolver allows for researchers and clinicians to quickly characterize morphometric courses and properties of a given structure. Paired with other scalar measurements, curvature can complete the picture of an anatomical structure's pattern.

SUBDIVISION OF THE OBJECT INTO SOLID POLYGONS AND ITS APPLIED AND ECONOMIC ASPECTS

In this article, we have studied an efficient algorithm by which we can efficiently divide a geometric object into convex components.Algorithms for dividing an object into convex polygons are among the main tools in computer graphics, robotics, and machine vision. These algorithms divide complex objects into simpler subsets consisting of convex polygons, which makes it possible to simplify their processing, analysis and visualization.Convex polygons have many advantages over more complex objects. First, they are easily described mathematically and can easily be stored in computer memory. Second, they have simple two-dimensional properties, which allows us to quickly determine their position in space. Third, convex polygons are easily sorted and processed using standard computer graphics algorithms.The described algorithm moves along all the internal angles of the object and checks whether that internal angle is greater than 180°, if so, divides the object by the continuation of the side forming that vertex. The advantage of our developed algorithm is the optimal partitioning of the object by dividing it into as few convex polygons as possible. And the shortcoming of the algorithm is its complexity.

Coupling interactions of anisotropic hyperbolic phonon polaritons in double layered orthorhombic molybdenum trioxide

The natural hyperbolic phonon polariton material-orthorhombic molybdenum trioxide (α-MoO<sub>3</sub>) has recently attracted much interest , due to the associated ultra-confinement of light and enhanced light-matter interactions. We theoretically propose and study the in-plane anisotropic phonon polaritons (APhPs) in the Kretschmann structure with monolayer and dual layers α-MoO<sub>3</sub>. The excitation of phonon polaritons and the corresponding dispersion properties in this multilayer system are studied by using a generalized 4×4 transfer matrix method (TMM). The frequency dispersions with geometrical parameters are also discussed in detail. The results confirm that the interlayer coupling can be modulated by stacking the multilayer films and regulating the thickness of each layer. More interestingly, when the distance between double α-MoO<sub>3</sub> layers is much smaller than the propagation length of PhPs, a strong coupling phenomenon occurs, and the photon tunneling probability and intensity can be greatly improved. When the incident angle is greater than the total internal reflection angle, the phase matching condition for SPhP excitation can be satisfied. Within the 40° incident angle, the SPhP blue-shifts rapidly with the increase of incident angle. But then the dispersion curve no longer changes with increase of incidence angle. The enlargement of the interstitial layer can also lead the Fabry-Perot (FP) resonance mode to be excited. The APhP in layered heterostructure is an important part of today's nanophotonic technology, our study can help optimize and design tunable optoelectronic devices based on hyperbolic materials.

Difference in implant design affects midflexion rotational laxity in cruciate-retaining total knee arthroplasty: a computer navigation study

PurposeThis study aimed to compare midflexion rotational laxity between two different design concept models of cruciate-retaining total knee arthroplasty: symmetrical surface design of neutral joint line obliquity and asymmetrical surface design of varus joint line obliquity.MethodsSixty-three knees that underwent cruciate-retaining total knee arthroplasty were evaluated. Manual maximum passive rotational stress without acceleration was applied to the knees under navigation monitoring. Pre-operative and post-operative internal and external rotational angles were measured at 30°, 45°, 60°, and 90° knee flexion.ResultsThe post-operative internal rotational laxity was significantly increased compared with pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 9.7° vs 11.1°, 10.6° vs 11.6°, 11.2° vs 12.9°, and 13.2° vs 14.9°; p = 0.01, 0.04, 0.001, and 0.008, respectively). The post-operative external rotational laxity was significantly decreased compared to pre-operative levels at 30°, 45°, 60°, and 90° flexion among all subjects (mean 10.8° vs 6.8°, 12.5° vs 9.4°, 12.8° vs 10.0°, and 11.3° vs 9.5°; p < 0.0001, < 0.0001, < 0.0001, and 0.0008, respectively). The post-operative total rotational laxity significantly decreased, compared with pre-operative levels, at 30° and 45° flexion among all subjects (mean 20.4° vs 17.9°, and 23.1° vs 21.1°; p = 0.002 and 0.04, respectively). The post-operative total rotational laxity was significantly smaller in asymmetrically designed total knee arthroplasty than in symmetrically designed total knee arthroplasty at 30°, 45°, and 60° flexion (mean 19.3° vs 15.8°, 22.8° vs 18.7°, and 24.4° vs 20.8°; p = 0.03, 0.03, and 0.02, respectively), whereas no significant difference was observed at 90° flexion.ConclusionCompared to symmetrical surface design, asymmetrical surface design resulted in lower rotational laxity at the midflexion range in cruciate-retaining total knee arthroplasty.Level of evidenceIII.

A Quasi-Square-Wave Modular Multilevel Resonant DC/DC Converter With ZCS and Current-Shaping Capacity for High Step-Ratio Application

High step-ratio dc/dc converter is one of the key equipments for dc grids to satisfy the requirement of interconnecting low voltage dc and medium voltage dc buses. This article proposes a high step-ratio modular multilevel resonant dc/dc converter, where two full bridges are connected in parallel at LV side, and two submodules (SMs) strings are connected in series at MV side. Due to the series connection of two SM strings, the number of SMs and the size of the passive filter at MV terminal can be significantly reduced. Moreover, with the quasi-square-wave (QSW) modulation, the proposed converter can achieve flexible current-shaping capability. On this basis, through an internal phase-shifted angle of QSW modulation, the output voltage can be regulated with a fixed switching frequency, simplifying the design procedure of magnetic components. And zero current switching turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> of full-bridge switches at LV side can be realized in forward and backward mode. In addition, based on the analysis of the operation principle with the time-domain method, the basic control strategy and parameter design procedure are introduced in detail. Finally, the feasibility of the proposed converter is validated by a 100 V/1 kV/4 kW prototype.

A new marker cluster anchored to the iliotibial band improves tracking of hip and thigh axial rotations

Tracking hip and thigh axial rotation has limited accuracy due to the large soft tissue artifact. We proposed a tracking-markers cluster anchored to the prominent distal part of the iliotibial band (ITB) to improve thigh tracking. We investigated if the ITB cluster improves accuracy compared with a traditionally used thigh cluster. We also compared the hip kinematics obtained with these clusters during walking and step-down. Hip and thigh kinematics were assessed during a task of active internal-external rotation with the knee extended, in which the shank rotation is a reference due to smaller soft-tissue artifact. Errors of the hip and thigh axial rotations obtained with the thigh clusters compared to the shank cluster were computed as root-mean-square errors, which were compared by paired t-tests. The angular waveforms of this task were compared using the statistical parametric mapping (SPM). Additionally, the hip waveforms in all planes obtained with the thigh clusters were compared during walking and step-down, using Coefficients of Multiple Correlation (CMC) and SPM (α = 0.05 for all analyses). The ITB cluster errors were approximately 25 % smaller than the traditional cluster error (p < 0.001). ITB cluster errors were smaller at external rotation angles while the traditional cluster error was smaller at internal rotation angles (p < 0.001), although the clusters’ waveforms were not significantly different (p ≥ 0.005). During walking and step-down, both clusters provided similar hip kinematics (CMC ≥ 0.75), but differences were observed in parts of the cycles (p ≤ 0.04). The findings suggest that the ITB cluster may be used in studies focused on hip axial rotation.

Stability risk assessment of slopes using logistic model tree based on updated case histories.

A new logistic model tree (LMT) model is developed to predict slope stability status based on an updated database including 627 slope stability cases with input parameters of unit weight, cohesion, angle of internal friction, slope angle, slope height and pore pressure ratio. The performance of the LMT model was assessed using statistical metrics, including accuracy (Acc), Matthews correlation coefficient (Mcc), area under the receiver operating characteristic curve (AUC) and F-score. The analysis of the Acc together with Mcc, AUC and F-score values for the slope stability suggests that the proposed LMT achieved better prediction results (Acc = 85.6%, Mcc = 0.713, AUC = 0.907, F-score for stable state = 0.967 and F-score for failed state = 0.923) as compared to other methods previously employed in the literature. Two case studies with ten slope stability events were used to verify the proposed LMT. It was found that the prediction results are completely consistent with the actual situation at the site. Finally, risk analysis was carried out, and the result also agrees with the actual conditions. Such probability results can be incorporated into risk analysis with the corresponding failure cost assessment later.

ELASTIC EMBEDMENT SUPPORT: A NOVEL APPROACH TO THE PRELIMINARY DESIGN OF SHAFTS

This study discusses the introduction of elastic embedment support in the preliminary design of shafts. The preliminary design of shafts idealizes the supports by considering them mobile articulated support, fixed articulated support, or embedded support. In several cases, these idealizations deviate from reality. While articulated supports produce internal forces, tensions, deflections, and gradients greater than real, embedded supports lead to internal forces, stresses, deflections, and deformation angles lower than real. These deviations in typical shaft design schemes have been corrected with safety factors. This study presents a novel elastic embedment support using a dimensionless stiffness coefficient to improve the preliminary shaft design and obtain more adequate results, with shaft dimensions more suitable for the acting loads. These results were assessed with the conventional analysis schemes for three bearing types for shaft lengths between 200 to 1000 mm. Contrasted to the conventional model articulating both shaft supports, the bending moment is significantly lower when considering the elastic embedment. The maximum bending moment from the conventional model is 65% higher than that obtained with the elastic embedment for single-row ball bearings, 58% higher for tapered roller bearings, and 40% higher for double-row ball bearings. Furthermore, the bending moment increases its significance with the shaft length. Thus, considering the bearing stiffness for the three rolling bearing types results in shaft support bending moments of 10 to 21% of the maximum bending moment obtained from the conventional model. These differences significantly impact the fatigue life estimation of the shaft because the deflection obtained from the conventional model is higher than that for the elastic embedded support, which impacts the fatigue life estimation of the shaft. Therefore, it is concluded that using the elastic embedment support in the preliminary shaft design, reduces the uncertainty in the results, leading to lower security coefficients. Keywords: Preliminary Shaft Design, Embedded Support, Articulated Support DOI： https://doi.org/10.35741/issn.0258-2724.58.1.47

Overcoming Gear Backlash With Flexible Shaft Using Disturbance Observer

The presence of backlash in gears with a flexible shaft is a challenging non-linearity that can cause vibration and noise, due to unstable torque, in the system which lead the system to unpleasant behavior and damage. In this paper, we are going to estimate the backlash angle to compensate the input torque to a simulated two-inertia system and overcome the torque instability in the system. The backlash non-linearity will be represented by the rigorous model proposed by Nordin et al. (2001) and carefully installed in an accurate simulation model, which gives the most effective platform for validation of controllers. Ignoring external loads, we are going to use Disturbance Observer (DO) to approximately estimate the internal backlash angle under flexible shaft condition. The estimated disturbance will be compensated and fed back to a torque controller to operate the system and overcome the unstable torque due to backlash. The simulation results showed that the driver motor torque accurately tracked the reference, in contrast with PID controller results without DO. However, the backlash estimation is not accurate, but it is synchronized with actual backlash angle. Therefore, in our further investigation, we are going to apply this scheme in our actual system and compare between simulation and experimental results using our new machine proposed in Shino (2022); Samadouny et al. (2023). Moreover, we will modify this scheme to estimate the backlash angle accurately.

Određivanje parametara smičuće čvrstoće na triaksijalnim uređajima

The soil properties are studied in mechanics, that is, the important properties according to which the soil can be classified. Based on mechanics, the information is being obtained on how the tested soil can be used. For example: which soil is favorable for the construction of various types of structures, which soil is favorable for the construction of embankments, etc. There are several ways to determine the elements of internal soil resistance, cohesion and angle of internal friction, using the laboratory tests, among which the most famous are the direct shear test, triaxial compression test and uniaxial compressive strength test. This paper will describe the "CU" triaxial test results.

Linking number and folded ribbon unknots

We study Kauffman’s model of folded ribbon knots: knots made of a thin strip of paper folded flat in the plane. The folded ribbonlength is the length to width ratio of such a folded ribbon knot. The folded ribbon knot is also a framed knot, and the ribbon linking number is the linking number of the knot and one boundary component of the ribbon. We find the minimum folded ribbonlength for [Formula: see text]-stick unknots with ribbon linking numbers [Formula: see text] and [Formula: see text], and we prove that the minimum folded ribbonlength for [Formula: see text]-gons with obtuse interior angles is achieved when the [Formula: see text]-gon is regular. Among other results, we prove that the minimum folded ribbonlength of any folded ribbon unknot which is a topological annulus with ribbon linking number [Formula: see text] is bounded from above by [Formula: see text].

The influence of new severe plastic deformation on microstructure, mechanical, and corrosion properties of Mg-0.8Mn-0.5Ca alloy

In this research, the effect of accumulative extrusion bonding (AEB) on the microstructure and mechanical properties of Mg-0.8Mn-0.5Ca biocompatible alloy was investigated. The goal of this research was to develop the mechanical and corrosion properties of Mg-0.8Mn-0.5Ca alloy after ABE process as a novel severe plastic deformation process. The simulation of AEB process showed that the average effective strain per pass for channels with the internal angle of 120? was about 1.93. The average grain size was dramatically decreased from about 448.3 ?m for the homogenized alloy to 1.55 ?m for the 3-pass processed sample. Microstructural observations suggested a combination of continuous, discontinuous, and twinning-induced dynamic recrystallization as the major mechanisms of grain refinement. Tensile and compressive strengths were improved from 150 and 205 MPa to 330 and 301 MPa after three passes of AEB, indicating 2 and 1.5 times improvements, respectively. Tensile elongation decreased from 26% for the homogenized sample to 7.5% for the 3-pass processed sample due to the severe work-hardening, non-uniform strains, and inhomogeneous microstructure produced by the ABE process. Corrosion resistance in SBF solution was improved from 1.1 to 14.159 after three passes of ABE due to the presence of hydroxyapatite formed on the surface of the AEBed samples.